Surfacing machine



Sept. 6, 1932. s, R ELL 1,876,202

SURFACING MACHINE Fild Feb. 13.. 1950 2 Sheets-Sheet l A TTORNEYS.

Sept. 6, 1932. s. R. CAMPBELL SURFACING MACHINE Filed Feb. 15. 195.0

2 Sheets-Sheet 2 III M llll WITNESSES INVENTOR ,Sem 1?. Campbell,

v TTOR NEYS.

Patented Sept. 6, 1932 3mm mm OFFICE sn'rn R. cnifrnnrgn, orynnooxnsMints, rENNsYLvANIA "suarAcr'Ne vmornnn Application filed February 13,1930. Serial No. 428,112.

This invention, while relating generally to surfacing machines, has(particular .application to rotary lapping machines of the, type shownin U. S. Letters Patent to VVyllis H 5 Markland, No. 1,515,743, issuedNovember of a work-holder supportedby and adapted to rotate with thesurrounding annulus. Machines :of thisvtype arecommonly used forreconditioningor lappingsmall valves, such as the moving parts of triplevalves, universal valves, distributing valves,v and the like.

The object vofthe present invention is to increase the capacity and theefliciency of such machines, and to this end I accomplish by theprovision of means which enable the; continuous operation of the machineLOVGI'. a comparatively long time without the necessity.

of resurfacing the grinding plate I Iereto fore it has beencharacteristic of such ma chines that the several articles being grounditravel over a variety of overlapping courses on the grinding plate, byreason .of the ec'-; centric relation of thegrinding plate'andvwork-holder, but each article of work repeats its own course, so thatthe Wearonthe' grinding plate, while somewhat. distributed over itssurfaces, is nevertheless non-uniform.

49 Accordinglythe grinding, plateshave to be resurfaced quitefrequently, and this isa factor tending to limit. materially the capaci:

ty of suchmachines. I On the other hand, the present-invention ischaracterized by a-relation between workholder and grinding plate whichpermits each article of work to travel over a'different course on' thegrinding plate at each rotation so that a particular point on one itemof work will describe an infinite number of courses withoutrepetition.Furthermore, the work may be so distributed that these courses willcover the entire surface of the grinding plate, with the result thatthere is a substantially uniform wear on the I grinding plate, thuseliminating the necessity of truing the'surfaceof-the plate, save aftera long period of operation.

fOther objects and; advantages attained by my invention will beapparentfrom the detailed description, which follows hereinafter, of"one form which the invention may take.

The description has reference to th 1 illustrated in the acment of theinvention companying drawings,

of which:

h Fig. Iis a top plan view of a rotarylapping machine ofmy inventionwith one work-holding tray in position'and the other removed, certainparts being broken away for clearnessf in illustration.

Fig. II is aside elevationof the upper part of thesame with a portion ofthe, grinding plate and its surrounding annulus shown in cross-section.

.- Fig. III is a cross-sectional view, of the machineof Fig. I takenalong the lines III III of Fig. I; and,

"I ig. IV'is a detailed cross-sectional View o'f-the brake'mechanismshown in Fig. III.

The machine shown is a rotary lapping machine comprising generally arotary grinding plate ;1, a surrounding carrier'Z in the form of. anannulus or bowl eccentric to'the grinding plate, and mechanism forcausing the grinding plate-to rotate in one direction and the bowliin areverse direction, the grinding plate in'the instance shown beingadapted to rotate at a speed five times greater than that of the bowl. f

The mechanism for driving the grinding plate 1 and the annulus or bowl 2is similar to that shown in the above mentioned Letters Patent of WyllisH. Markland and forms no part of this invention. Briefly it comprises aframe 3, which may conveniently be a part of a table or work bench, anda number of shafts and gears for transmitting power applied at thepulley 4 to the grinding plate shaft 5 and to the gear ring 6 on theannulus 2. The grinding plate shaft 5 is driven by a pulley shaft 7through bevel gears 8 and 9. An additional gear 10 on the grinding plateshaft 5 engages an idler 11 which in turn drives a pinion 12 on a shaft13. The shaft 13 through an additional pinion 14 drives the annulus 2,the pinion 14 engaging the gear ring 6 on the underside of the annulus2, causing the same to rotate about the eccentric hub 15 on the frame 3.On the grinding plate shaft 5 is a driving plate 16 provided with ascrew 17 near its perimeter. The screw 17 is adapted to engage one of aset of similar screws 18 used for levelling the grinding plate. Thisfurnishes a positive drive, while permitting the grinding plate to beeasily removed. Suitable arrangement, which need not be here described,is made for oiling the various shaft bearings.

The mechanism thus far described effects the opposite rotation at apredetermined speed ratio, say five to one, of the grinding plate 1 andthe surrounding eccentric annulus 2.

Centrally of the grinding plate 1 there is an annular recess 19 designedto accommodate a floating plate 20. This plate 20 has merely africtional engagement with the grinding plate 1 so that it will float onthe grinding plate unless otherwise restrained. A disc 21 is internallythreaded to engage corresponding threads on the floating plate 20, and aset screw 22 is provided to enable an adjustment between the disc 21 andfloating plate 20 for reasons hereinafter pointed out, these parts beingheld in fixed relation by he set screw 22 while the machine is inoperation. The floating plate 20 and the superimposed disc 21 togetherconstitute a workholder support.

Eccentrically mounted on the disc 21 are a threaded pin 23 and a ballrace 24, these parts serving as a bearing for the workholder or carrier25. The pin 23, though off center from the grinding plate 1, is centeredwith respect to the annulus or bowl 2, when the parts are in theposition shown in the drawings. The work-holder 25 is always eccentricto the grinding plate 1 and at times concentric with the annulus or bowl2. A

a cap 26 engages thefupper threads of the pin 23 and serves to hold thework-holder 25 in place, while permitting its ready removal. The cap 26is recessed at 27 so that it does not come in frictional contact withthe workholder 25.

The work-holder 25 comprises a spider frame adapted to accommodate inits semicircular openings 28 removable trays 29 which carry the work tobe ground. The trays 29 are provided with openings 30 of a size toaccommodate the particular type of work. I preferably employ a series ofsuch trays with openings of a variety of shapes suiting the parts whichare customarily resurfaced on the machine. The trays 29 are retainedwithin the work-holder 25 by flexible metal straps 31 having slots 32engaging pins 33 on the work-holder which permit a limited slidingmovement of the straps around the work-holder. The straps 31 areprovided with lugs 34 forming additional slots 35 which are adapted toengage and disengage projections 36 on the trays 29. Tension springs 37with one end attached to a strap 31 and the other attached to theworkholder 25 tend to rotate the straps 31 to the position shown at theleft hand of Fig. I, in which position the trays 29 may be lifted fromthe work-holder 25. The straps are also provided with finger grips 38.By pressing the finger grips 38 together the straps wlll be rotatedaganst the pressure of the springs 37 about the work-holder 25 and thetray projections 36 will be caught in the slots 35 as shown at theright-hand of Fig. H. The straps 31 when so moved are automaticallylocked by pins 39 on the spring pressed angle members 40, the pins 39fitting in corresponding holes 41 in the work-holder 25. To release thestraps 31 the angle members 40 are pressed against the springs 42releasing the pins 39 from the holes 41 and permitting the tensionsprings 37 to return the straps 31 to their original position.

The work-holder 25 has an arm 43 affixed f; thereto by screws 44. Thearm 43 is slotted at 45 and adapted to move with a reciprocatory motionabout a pin 46 with a knurled knob 47 and lower threaded portionengaging the head of a screw 48. This screw 48 in turn fits in athreaded opening in the rim of the annulus 2. It may be turned to adjustthe level of the surface upon which the arm 43 bears. By this adjustmentand the further adjustment afforded by the threaded floating plate 20turning within the disc 21, all the parts may be levelled and verticallyaligned to compensate for a changein thickness of the grinding plate 1or wear on the contacting surfaces of other moving parts.

Housed within the work-holder 25 is a brake mechanism comprising a brakerod 49 carrying a brake shoe 50 adapted to engage and disengage thefloating disc 21. The brake rod 49 has a threaded end 51 fitting acorrespondingly threaded opening in an arm 52 which is adapted to slideback and forth within the cavity 53. The brake shoe 50 is pivoted at 54on the brake rod 49 and the shoe is normally held apart from the disc 21by means of a spring 55 which forces the arm 52 outward until itsshoulder 56 strikes a stop 57 on the work-holder 25.

It will be apparent from the description thus far that the rotarymovement of the grinding plate 1 will cause a similar movement ofthefloating plate and disc 21 which will effect a rotation of the axis of pthe work-holder 25. The work-holder being connected by the arm 43 to theannulus 2 will, of course, make one revolution for every revolution ofthe annulus", but its center will at the same timesmake five revolutionsu about the center of the grinding plate 1, causing a reciprocatorymovement of the arm 43 with five double strokes for each revolution ofthe annulus. During four doublestrokes of the arm 43, the brake arm 52will not strike the rim of the annulus 2 on account of the 22 spacebetween the grinding plate 1 and annulus 2 being sufficiently wide topermit the brake arm 52 to travel back and forth with the work-holderarm 43, but at one point in the operation of the machine (when the ele-259 ments are in the position shown in the drawings), the space betweenthe grinding plate.

1 and annulus 2 is so restricted that the brake arm 52 in passing willstrike the annulus and be moved inward a short distance, thus applym thebrake shoe 50 to the floating disc 21 for an instant. When the brakemechanism is operated the floating plate 20 and disc 21 will berestrained from rotating with the grinding plate 1, and will besubjected to the rotary movement of the annulus 2. Accordingly, the

axis of rotation of the work-holder will remain stationary for aninstant with respect to the annulus 2. This will efiect a change in theangle a b 0 between a point on the grinding plate, the center of thegrinding plate,

and the axis of rotation of the work-holder, which in turnwill eflect achange in the course which a point of the face of an article beingground will describe on the grinding plate.

To adjust the operation of the brake, I provide a set screw 58 so thatthe total length of the brake rod 49 and brake arm 52 may be varied andset at the desired measure.

The hub portion 59 of the work-holder 25,

except for the instant at which the brake is applied, rotates in theopposite direction from that of the disc 21. To provide a wearingsurface on the disc 21 I form the disc with a raised portion 60 in theform of a circular 55 track eccentric to the disc 21 but concentric withthe hub 59.

The operation of the machine will be apparent from the description ofits constituent elements. If the brake mechanism were not employed, thepath of each article of work would constitute a definite cycledistributed over the face of the grinding plate, but repeating itself.However, each time the annulus 2 completes a revolution, the applicationof the brake changes the angle between a point on. the grinding plate,the center of the grinding plate and theaxis of rotation of thework-holder, so that a new path or course is described. Theoretically acircle may be divided into an infinite number of degrees and fractionsthereof so that the machine may be accurately described as operatupon aprinciple permittingthev Work to describe an infinite number of coursesover the grinding plate. As a practical matter. thereis, of course, alimitation on the opera: tion without repetition (the period ofapplication of the brake mechanism cannot be re duced beyond acertainpoint) but this limitation does not effect the practical operationofmachines embodying my invention,because a repetition of the coursedescribed by a point on the work being ground, 1f it does occur, 1

will occur so infrequently that the grinding plate will wearuniformlythroughout, this wear being distributed over its entire surface.

sitions of the axes-of work-holder and grinding. plate, resulting asitdoes in the uniform wearing of the surface of the grinding plate,renders it commercially practicable toincrease thecapacities' ofmachines of this type andaifords other advantages which will be manifestto those skilled in this art.

l/Vhile my invention has been described in some detail with respect to aspecific embodiment thereof, it will, of course, be apparent thatvarious changes maybe made in the particular form here illustrated anddescribed without departing from the spiritof the invention, as claimed.

Having thus described my invention, I

claim:

1. A. surfacegrinding machine including a rotary grinding plate, asurrounding annu lus eccentric to said grinding plate. and

The automatic changing of the relative po- 7 adapted to begrotated inthe oppositedirec-- eccentric to said grinding plate and adapted foroppositerotation, a floating plate frictionallyengaging said grindingplate, a bearing eccentrically mounted on said floating plate, awork-holder on said bearing adapted 1 to rotate with the said annulus,and means 1 whereby said floating plate is at times subected to therotary movement of said grinding plate and at times subjected to therotary movement of said annulus. 3. A surface grlnding machine includinga rotary grinding plate, a surrounding annulus eccentric to saidgrinding plate and adapted for opposite rotation, a floating platefrictionally engaging said grinding plate, a bearing eccentricallymounted on said floating plate, a work-holder on said bearing andadapted to rotate with said annulus, and a brake adapted to engageintermittently said floating plate to subject the .same to the rotarymovement of said annulus.

4. A surface grinding machine including a rotary grinding plate, asurrounding annulus eccentric to said grinding plate and adapted foropposite rotation, a floating plate frictionally engaging said grindingplate, a bearing eccentricaily mounted on said floating plate, awork-holder on said bearing adapted to rotate with said annulus, a brakenormally separated from said floating plate, and a reciprocatory arm forcausing said brake upon each revolution of the annulus to bear upon thesaid floating plate for an instant to subject the same to the rotarymovement of said annulus.

5. A surface grinding machine including a rotary grinding plate, asurrounding annulus eccentric to said grinding plate and adapted foropposite rotation, a floating plate frictionally engaging said grindingplate, a bearing eccentrically mounted on said floating plate, awork-holder on said bearing adapted to rotate with said annulus, andmeans for adjusting the vertical position of said bearing with respectto said floating plate.

6. A surface grinding machine including a rotary grinding plate, asurrounding annulus eccentric to said grinding plate and adapted foropposite rotation, a pin on said annulus, a work-holder having a centralbearing rotatingwith said grinding plate, the axis of said worloholderbeing eccentric to the axis of said grinding plate, and a slotted armengaging the pin on said annulus whereby said work- .holder is adaptedfor relative reciprocatory and rotary movement with respect to saidgrinding plate.

7. A surface grinding machine comprising a carrier, a grinding platerotatable with respect to said carrier, a work-holder eccentric to thegrinding plate and engaged by said carrier, 21 worloholder supportnormally subject to the rotation of said grinding plate, and meansperiodically acting upon said work-holder support to connect saidsupport with said carrier so that said support ceases to rotate withsaid grinding plate, thereby effecting a change in the relativepositions of the axes of said grinding plate and work holder.

8. A surface grinding machine comprising a carrier, a grinding platerotatable with respect to said carrier, a work-holder eccentric to thegrinding plate and engaged by said carrier, a work-holder supportnormally sub-

